Health Service Use and Costs During Pregnancy Among Privately Insured Individuals With Congenital Heart Disease

Key Points Question What are the health care use and costs among patients with congenital heart disease (CHD) during pregnancy? Findings In this cohort study of 11 703 pregnancies, 2267 pregnancies in 1785 patients with CHD incurred $8319 and $700 higher total and out-of-pocket costs per pregnancy, respectively, than 9436 pregnancies in 7720 patients without CHD. For patients with CHD, pregnancy-related medical conditions and birth outcomes, as opposed to CHD anatomic severity, were associated with longer length of stay and higher costs. Meaning These population-based estimates provide novel and critical data for financial planning and advocacy for adequate resources and workforce to improve care for the increasing population of patients with CHD reaching childbearing age.

2][3][4] If an ICD code for CHD was present on ≥2 outpatient claims separated by >30 days or ≥1 inpatient claim at any billing position during the period of enrollment, these patients were then considered to have CHD.For patients with codes for more than one CHD diagnosis, we used the hierarchical algorithm proposed by Broberg et al. 4 to designate one condition per patient as their principal CHD diagnosis.The principle of the hierarchy is that physiologically more severe or complex lesions take precedence over less severe or simpler ones.We excluded any patients who had CHD diagnoses codes documented only during pregnancy or delivery-related claims (see below for the pregnancy algorithm) to avoid inclusion of pregnant women with fetuses affected by CHD.We also excluded claims with ICD codes for nonspecific CHD diagnosis such as atrial septal defect (due to lack of differentiation with patent foramen ovale); unspecified congenital heart, pulmonary artery, aortic, or great vein anomalies; and congenital heart block. 3,4The remaining patients were categorized based on their anatomic severity as 1) Severe CHD: Eisenmenger Syndrome, single ventricle, hypoplastic left heart syndrome, transposition of great arteries, Tetralogy of Fallot, truncus arteriosus, and endocardial cushion defect; and 2) Nonsevere CHD: coarctation of aorta, anomalies of the pulmonary artery or pulmonary valve, anomalies of the tricuspid valve (including Ebstein's anomaly), ventricular septal defect, patent ductus arteriosus, unspecified septal defects, anomalous pulmonary venous return, subaortic stenosis, aortic anomalies, anomalies of the aortic or mitral valve, anomalous coronary artery and other congenital heart anomaly.Since Ailes et al primarily used ICD 9 codes, we used the corresponding ICD 10 codes from other validated studies. 6,7Briefly, we used inpatient and outpatient services files to identify all the claims that mapped to one of the diagnosis, procedure, or Diagnosis Related Group (DRG) codes indicative of a birth outcome (eTable 2).We prioritized the codes in the following order: 1) diagnosis codes, 2) DRG codes, and 3) procedure codes.If birth outcomes were still discrepant, we assigned one using the following hierarchy: 1) stillbirth, 2) live birth, 3) induced abortion, 4) spontaneous abortion, 5) abortion of unknown type, and 6) ectopic pregnancy.We assigned GA using the records with the selected birth outcome.If more than one GA estimate was present, we used the minimum GA to avoid overestimating exposure during pregnancy.If a visit indicated a full-term delivery without a code indicating a more specific GA, we estimated that to occur at 40 weeks of gestation.LMP was estimated as the admission (for inpatient visits) or service (for outpatient visits) date minus the GA.To differentiate visits associated with separate pregnancies, we required ≥ 2 months between one birth outcome and the LMP of the next pregnancy.For those pregnancies that could not be differentiated, we prioritized the inpatient followed by outpatient service claims and applied the above hierarchy of diagnosis/ procedure codes, then re-assigned birth outcomes, determined GA as above and estimated the LMP.Multiple births were included, but, due to the limitations of claims data, we could not distinguish a multiple birth from a singleton birth unless the birth outcomes differed between the multiples (e.g, combination of live birth[s] and stillbirth[s]).
To capture the entire pregnancy time range, we only included pregnancies that were completely enrolled in a contributing commercial insurance from 60 days before LMP through 90 days after delivery.Pregnancies conceived in 2009 and ending in 2010 or conceived in 2016 and ending in 2017 were thus excluded in the analytic sample.To differentiate visits associated with separate pregnancies, we required ≥ 2 months between one birth outcome and the LMP of the next pregnancy.In case of any overlap between two pregnancies, the associated visits were included in the previous pregnancy.We used the ICD codes and algorithms described previously to identify obstetric conditions (gestational diabetes mellitus [GDM], hypertensive disorders of pregnancy, or preterm premature rupture of membranes [PPROM] or preterm labor/delivery) [7][8][9][10] for patients whose pregnancy lasted for more than 20 weeks of gestation.Women with a diabetes mellitus diagnosis code (ICD 9: 250, 648.0, 790.2;ICD10: O24.0, O24.1, O24.3, O24.8, E08-E13, R73.0, or R73.9) from 2010 to 2016 before a GDM diagnosis code were not classified as having GDM; as previously described. 9veral tools are available to identify medical conditions in administrative data. 11We used the ICD codes as listed by the Agency for Healthcare Research and Quality (AHRQ) Elixhauser comorbidity measures to identify majority of the cardiac and noncardiac conditions during pregnancy (eTable 3). 12The AHRQ measure however does not include some conditions that are important in CHD and/or pregnancy, so we used the AHRQ's single-level Clinical Classification System (CCS) 13  Compared to nonCHD, pregnancies in patients with CHD had significantly higher healthcare use in all categories (standardized mean differences [SMDs] ranging from 0.19 [p<0.001] for inpatient admissions to 1.72 [p<0.001] for outpatient cardiologist visits) and significantly higher costs in all categories (SMDs ranging from 0.15 [p<0.001] for ED visits to 0.63 [p<0.001] for outpatient physician visits) except for out-of-pocket inpatient and out-of-pocket emergency department costs (eTable 4).

eAppendix 1 . 2 . 3 .
Congenital Heart Disease (CHD) Algorithm eTable 1. Congenital Heart Disease (CHD) Lesions and Their International Classification of Disease (ICD) Diagnostic Codes eAppendix 2. Pregnancy Algorithm eTable Diagnostic and Procedure Codes Used for Birth Outcomes, Pregnancy Timings and Cesarean Section eAppendix Identifying Conditions: Obstetric, Cardiac, and Noncardiac eTable 3. Obstetric, Cardiac, and Noncardiac Conditions eFigure 1. Study Population eAppendix 4. Subanalysis of Patients With Livebirth Pregnancies eTable 4. Health Service Use and Costs Among Livebirth Pregnancies eFigure 2. Adjusted Total (2A) and Out-of-Pocket (2B) Cost Differences During Pregnancy With Livebirth in Patients With and Without Congenital Heart Disease eReferences This supplementary material has been provided by the authors to give readers additional information about their work.

eAppendix 1 .
Congenital Heart Disease (CHD) Algorithm Abbreviations: CHD = congenital heart defects, ED = emergency department, SD = standard deviation, IQR = interquartile range a Includes Obstetric physician, birth center and midwife visits.b The summary statistic is based on the patients who have any admissions in the pregnancy time range.c Component costs are calculated only for patients who had the service.d Total Nonphysician outpatient costs and out-of-pocket costs includes any outpatient visit which is non-ED and nonphysician but that occurred in the pregnancy time range.e p values were obtained using student t-test or Wilcoxon rank sum test as appropriate.

eFigure 2 .
Adjusted Total (2A) and Out-of-Pocket (2B) Cost Differences During Pregnancy With Livebirth in Patients With and Without Congenital Heart Disease

eTable 2 .
Diagnostic and Procedure Codes Used for Birth Outcomes, Pregnancy Timings and Cesarean a If a claim or visit included codes with different pregnancy outcomes, we prioritized code types in the following order: 1) information from diagnosis codes, 2) information from DRG codes, and 3) information from procedure codes.If pregnancy outcomes were still discrepant, we assigned a pregnancy outcome using the following hierarchy: 1) stillbirth, 2) live birth, 3) induced abortion, 4) spontaneous abortion, 5) abortion of unknown type, and 6) ectopic pregnancy.b Unless the visit had a code indicating a pre-or post-term delivery c Infant code Abbreviations: GA=gestational age, ICD = International Classification of Diseases, CPT = Current Procedural Terminology, HCPC=Healthcare Common Procedure Coding System codes, DRG= Diagnosis Related Groups eAppendix 3. Identifying Conditions: Obstetric, Cardiac, and Noncardiac Subanalysis of Patients With Livebirth Pregnancies Between 2010 and 2016, there were 1,418 patients with CHD contributing 1,649 pregnancies (348 pregnancies among 302 patients with severe CHD and 1,301 pregnancies among 1,116 patients with nonsevere CHD) and 6,419 patients without CHD contributing 7,275 pregnancies.The mean (standard deviation [SD]) patient age was 31.4 (5.1) years.
codes to identify the ICD codes for determining conditions such as coronary artery disease, stroke, deep venous thrombosis, pulmonary embolism, and infective endocarditis.The CCS provides a way to classify diagnoses and procedures into a limited number of categories by aggregating individual ICD codes into broad diagnosis and procedure groups to facilitate statistical analysis and reporting.For determining coronary dissection, peripartum cardiomyopathy and seizure during pregnancy, we used the previously published ICD 9 codes 8 and supplemented the corresponding ICD 10 codes using the CCS classification.All the conditions, except obstetric conditions, were identified if documented during the pregnancy time range i.e. from 60 days before the last menstrual period to 90 days postpartum per pregnancy; we did not assess whether any of the condition was first diagnosed during pregnancy.